Comparing two files, if two characters on the same col don't match, cout it. Works

Comparing two files, if two characters on the same col don't match, cout it. Works

This is a discussion on Comparing two files, if two characters on the same col don't match, cout it. Works within the C++ Programming forums, part of the General Programming Boards category; Code:
#include <iostream.h>
#include <stdlib.h>
#include <fstream>
#include <string>
int main()
{
std::ifstream tfile("C:/test.dat");
std::ifstream tfile2("C:/test2.dat");
char tdata[15000000];
char tdata2[15000000];
...

This code worked better before, but then I messed with it. Anyway, the code worked perfectly on small files, but the files I want to compare are 700-800k big. I don't know if there are characters in those files which the program can't take or if it is something else.

If anyone knows what might be the problem, or if there's any real program for this, please let me know.